up to 600v dc in 400 volts dc out charge controller?

[XeonPony]

With the nissan leaf gaining ground and flooding killing cars leaving the batteries other wise healthy, it comes to mind to get a few packs and perallel them, then charge them directrly from a pv array.

then find an inverter to directly down convert or use a dc-dc converter to a standered Xw series inverter.

Doing it this way I can take advantage of every thing including the BMS cell balancing system and interconect them via the can bus controller.

Any thoughts?

[Frank S]

 Trip-lite makes high voltage inverters  with DC input voltages in the 196 to 240v range  even PSW 3 ph 20 to 40KW  and larger UPS  pricey though.

[Mary B]

Surprised the salt water hasn't killed the packs too

[joestue]

i seem to recall someone that made inverters that run at up to 600 volts?

if you can keep the voltage below 500/550 i would build my own H bridge from 600/650 volt mosfets and run a 60 hz transformer directly, spending a reasonable amount of money to get an LC filter in front of it working properly to keep the harmonics out of the transformer.. but that might not be needed, depending on the frequency, the transformer can be used as the inductor. a 20uF cap on the output is all you need.
I would also consider switching out 2 or more transformers operating in parallel to keep parasitic draw low. a 1Kva toroid for example, in parallel with a 240/120:240/120 5 KVA buzz box running a 50C no load temperature rise would be an appropriate match for instance.
by the time you get to 2Kva the copper loss in the toroid matches the iron loss in the buzzbox.

500*80% / 1.41 is 283 volts, so if you can find a 480 volt Y three phase transformer you could reconfigure it for delta. the secondary is of course another variable.

i would consider building a buck converter and driving a second inverter as a last resort because that requires work, and another inverter.

also switching 500 volts is really noisy, parasitic capacitance gets in the way.
running 60hz pwm at 8Khz into a 60 hz transformer is one thing, 100Khz into an LC filter is another.
I suppose you could run air core inductors for the buck converter.

it will also need to be properly compensated or you could end up blowing up the downstream inverter instantly.

it doesn't take a lot of work to fool a VFD into running at higher than, or lower than normal voltage, and you could replace the IGBTs with mosfets to reduce parasitic draw at the expense of throwing more money at it.

i don't know if my 480volt AB1305 will run at 400-500 volts, i think it needs at least 600 before it thinks the supply is high enough, but the flyback supply inside it will turn on and run well below that.. so the voltage sense line could be found and bypassed...

i wouldn't risk running a 240vac VFD on 500 volts dc but who knows, they might survive, everything in there is probably rated for 600 volts.

[XeonPony]

ok there is indeed a thought, just make the inverter, I kind of wanted all the logging stuff that came with them, I can build a simple hbridge drive and a LC filter, but the soft ware to drive it is out of my reach. I'm great with hard ware, not so much soft ware (Last simple step motor driver I made was over 16 pages long in qbasic!

[joestue]

Xeon, are you interested in a buck converter for such a topology?

the reason i ask is because i need to build such a device anyways on the order of several kilowatts for controlling the power flow through an induction heater. (in my case, taking 400 volts from a PFC converter and dropping it down to 0-400 volts)

basically the voltages don't matter, i've got some 300 amp 1200 volt igbts.. but the hard points are
1) charging up the boot strap drive
2) measuring input current
3) measuring output current

solving those three things can be done any number of ways, but safe operation at 600 volts requires 900-1200 volt rated parts.
basically requires optical or magnetic isolation.